[cwconfig] Issue a warning if a configuration module cannot be loaded
We already do this when loading ctl plugin modules, so make things symmetrical
for config modules.
3.25 (UNRELEASED)
=================
New features
------------
* A new option `connections-pooler-enabled` (default yes) has been added. This
allow to switch off internal connection pooling for use with others poolers
such as pgbouncer_.
.. _pgbouncer: https://pgbouncer.github.io/
* A new way to declare workflows as simple data structure (dict/list) has been
introduced. Respective utility functions live in ``cubicweb.wfutils``
module. This handles both the creation and migration of workflows.